The present invention relates to a permanently anti-microbial and flame-retardant yarn and fabric made therefrom, and more particularly to such a yarn having a unique construction.
There are few situations in which it would not be considered advantageous for a yarn to be flame-retardant. Similarly, there are few situations in which it would not also be considered desirable for such a flame-retardant fabric to also be anti-microbial (i.e., anti-bacterial, anti-fungal, anti-mildew, anti-mold, etc.). Among the many situations where it is important that a fabric exhibit both flame-retardant and anti-microbial characteristics are cubicle fabrics (that is, the privacy curtains used in hospital cubicles to separate one patient from another), shower curtains (where the anti-microbial feature retards the growth of mildew), draperies, bedspreads, etc. Perhaps the most difficult application of all is the cubicle fabric which must be capable of maintaining the desired flame-retardant and anti-microbial characteristics even after being subjected to numerous commercial launderings.
Among the most stringent and well-known tests for these characteristics are the National Fire Protection Agency (NFPA) vertical flame-retardancy test NFPA 701 (an 1989 version) and the anti-microbial test of NYS 63 for a percentage reduction level in the gram negative and gram positive bacteria. The vertical flame-retardancy test is specified by governmental authorities or contractors for many applications, and a fabric either passes the test or it does not. Typically, in order to meet the requirement, as a flame is brought close to a fabric, the fabric must undergo only a limited amount of burning. The anti-microbial test merely sets forth the test procedure to be used, allowing the manufacturer to specify the reduction level which is provided by a given fabric. A fabric which is to be used as a bandage, in actual contact with a wound, might require a very high bacteria reduction level of 99% or so (because it might be in contact with an open wound), while a cubicle fabric or shower curtain (which is not intended to be in contact with an open wound) may require only an 85% reduction level, or even less.
It is known both to produce a permanently flame-retardant yarn and to produce a permanently anti-microbial yarn. Nonetheless, the production of a yarn which is both permanently flame-retardant and permanently anti-microbial is not a simple matter. In order to produce the desired anti-microbial effect on bacteria (both gram positive and gram negative), fungus, mildew and the like, it is necessary that the anti-microbial material be present in at least a certain minimum local concentration. In other words, the dispersion of the anti-microbial material throughout a fabric may be ineffectual to fight microbes, while the disposition of the same quantity of anti-microbial material in or about a relatively small area of the fabric may be effective to provide an anti-microbial effect in at least that area. On the other hand, as one increases the amount of anti-microbial material, the effectiveness of the flame-retardant material is diminished. After a certain point, where the applicable flame-retardant test cannot be meet, this is simply unacceptable. In any case, the anti-microbial material is typically about three times as expensive as the flame-retardant material so that it is economically desirable to use the minimum amount of the anti-microbial material effective for a given application.
Accordingly, it is an object of the present invention to provide a permanently flame-retardant and anti-microbial yarn.
Another object is to provide such a yarn wherein, in one preferred embodiment, the anti-microbial filaments thereof are disposed so as to maximize the anti-microbial effect therefrom while minimizing both the cost thereof and the negative effect thereof on the flame-retardant filaments thereof.
A further object is to provide a knit or woven fabric formed with such a yarn.
It is also an object of the present invention to provide such a knit or woven fabric which, in one preferred embodiment, is characterized by an ability to pass, both after one commercial laundering and after 100 commercial launderings, both National Fire Protection Agency vertical flame-retardancy test NFPA 701-1989 (the 1989 version) and at least the 85% reduction level of gram positive and gram negative bacteria of anti-microbial test NYS 63.